Structural and Functional Changes of Cervical Neuromuscular System Associated with Insidious Onset Mechanical Neck Pain: A literature Review.

Background: The purpose of this review is to provide an updated overview of structural and functional changes of cervical neuromuscular system associated with Insidious Onset Mechanical Neck Pain [IOMPT]. Methods: MEDLINE and SCOPUS databases were searched. Observational studies published after 01-01-2003 in English or Italian languages were included. The following search string was used: “neck pain" AND (muscle OR “motor control” OR behaviour OR function OR endurance OR “isometric contraction”) NOT (radiculopathy OR surgery OR "specific neck pain"). Results: 15 papers concerning changes in structure of neck neuromuscular system, 19 on changes in pattern of neuromuscular activation, and 16 on deficit in neuromuscular function associated to IOMNP were selected. From this review emerges that pain, whether it be artificially produced or due to IOMNP, provokes an alteration of the cervical region function and a number of anomalies in the behavior of the neuro-muscular system. IOMNP is associated with structural alterations affecting the cervical region at different levels (metabolic, histological, and even macroscopic). Changes in cervical neuromuscular system structure concern altered histology and metabolism, cross sectional area thickness, muscle fatty infiltration, trigger points generation, and alterations of muscular activation pattern. Changes in neuromuscular function concern reduced maximal voluntary contraction, alteration on proprioception, coordination and on complex functions. Conclusion: The relationships between IONMP and changes in the intrinsic properties, behavior, and function of neck muscles have now acquired evidence. There is a widespread consensus about the fact that these alterations contribute to the onset, maintenance, and recurrence of neck pain.